Field of the Invention
The invention relates to methods and compositions for nanorods.
Related Art
Metal nanorods have received widespread interest due to their unique one-dimensional structure, their consequent unusual optical, electronic and catalytic properties, and their potential use in chemical sensing, cellular imaging and therapeutics. Specifically, noble metal Au (Jana, 2001; Nikoobakht, 2003; Gole, 2004; Sau, 2004; Kou, 2007), Ag (Zhang, 2011), Pt (Krishnaswamy, 2006; Peng, 2009) and Pd (Xiong, 2007a; Xiong, 2007b; Lim, 2009; Chen, 2009) nanorods have garnered great interest, among which Au nanorods have been most extensively studied due to their plasmonic activity. Most conventional syntheses rely on solution-phase reactions, e.g., seed-mediated growth for the synthesis of Au nanorods (Jana, 2001; Nikoobakht, 2003; Gole, 2004; Sau, 2004; Kou, 2007). The yield of nanorods relative to byproducts such as spheres and the sensitivity of the reaction to various parameters (and thus the reproducibility) (Millstone, 2008) have been major concerns in many circumstances.
Templating methods have also been pursued to synthesize metal nanorods by employing porous alumina membranes and polycarbonate filtration membranes as hard templates (Kyotani, 1997; van der Zande, 1997; Cepak, 1998; Martin, 1999; van der Zande, 1999; Kyotani, 1997; van der Zande, 1997; Cepak, 1998; Martin, 1999; van der Zande, 1999). Typical limitations of such templating synthesis include the difficulty in controlling both the width and length of the products, low yield because only a monolayer of metal nanorods could be prepared in a membrane template, and the high cost associated with these templates. In general, a practically useful templating method for nanostructure synthesis should meet the following requirements: (1) the convenient availability of well-defined templates in large quantity at low cost; (2) the precise placement of seeds inside the templates; (3) a well-controlled seeded growth process; and (4) a reliable process to selectively remove the templates.